CCAMP Working Group Chris Hopps (Cisco)
Internet Draft Lyndon Ong (Ciena)
Category: Informational Dimitri Papadimitriou (Alcatel)
Jonathan Sadler (Tellabs)
Expiration Date: December 2006 Stephen Shew (Nortel)
Dave Ward (Cisco)
May 2006
Evaluation of existing Routing Protocols
against ASON routing requirements
draft-ietf-ccamp-gmpls-ason-routing-eval-03.txt
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Abstract
The Generalized MPLS (GMPLS) suite of protocols has been defined to
control different switching technologies as well as different
applications. These include support for requesting TDM connections
including SONET/SDH and Optical Transport Networks (OTNs).
This document provides an evaluation of the IETF Routing Protocols
against the routing requirements for an Automatically Switched
Optical Network (ASON) as defined by ITU-T.
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1. Contributors
This document is the result of the CCAMP Working Group ASON Routing
Solution design team joint effort.
Dimitri Papadimitriou (Alcatel, Team Leader and Editor)
EMail: dimitri.papadimitriou@alcatel.be
Chris Hopps (Cisco)
EMail: chopps@rawdofmt.org
Lyndon Ong (Ciena Corporation)
EMail: lyong@ciena.com
Jonathan Sadler (Tellabs)
EMail: jonathan.sadler@tellabs.com
Stephen Shew (Nortel Networks)
EMail: sdshew@nortelnetworks.com
Dave Ward (Cisco)
EMail: dward@cisco.com
2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
The reader is expected to be familiar with the terminology introduced
in [RFC4258].
3. Introduction
There are certain capabilities that are needed to support the ITU-T
Automatically Switched Optical Network (ASON) control plane
architecture as defined in [G.8080].
[RFC4258] details the routing requirements for the GMPLS routing
suite of protocols to support the capabilities and functionality of
ASON control planes identified in [G.7715] and in [G.7715.1]. The
ASON routing architecture provides for a conceptual reference
architecture, with definition of functional components and common
information elements to enable end-to-end routing in the case of
protocol heterogeneity and facilitate management of ASON networks.
This description is only conceptual: no physical partitioning of
these functions is implied.
However, [RFC4258] does not address GMPLS routing protocol
applicability or capabilities. This document evaluates the IETF
Routing Protocols against the requirements identified in [RFC4258].
The result of this evaluation is detailed in Section 5. Close
examination of applicability scenarios and the result of the
evaluation of these scenarios are provided in Section 6.
ASON (Routing) terminology sections are provided in Appendix 1 and 2.
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4. Requirements - Overview
The following functionality is expected from GMPLS routing protocols
to instantiate the ASON hierarchical routing architecture realization
(see [G.7715] and [G.7715.1]):
- Routing Areas (RAs) shall be uniquely identifiable within a
carrier's network, each having a unique RA Identifier (RA ID)
within the carrier's network.
- Within a RA (one level), the routing protocol shall support
dissemination of hierarchical routing information (including
summarized routing information for other levels) in support of an
architecture of multiple hierarchical levels of RAs; the number of
hierarchical RA levels to be supported by a routing protocol is
implementation specific.
- The routing protocol shall support routing information based on a
common set of information elements as defined in [G.7715] and
[G.7715.1], divided between attributes pertaining to links and
abstract nodes (each representing either a sub-network or simply a
node). [G.7715] recognizes that the manner in which the routing
information is represented and exchanged will vary with the
routing protocol used.
- The routing protocol shall converge such that the distributed
Routing DataBases (RDB) become synchronized after a period of
time.
To support dissemination of hierarchical routing information, the
routing protocol must deliver:
- Processing of routing information exchanged between adjacent
levels of the hierarchy (i.e. Level N+1 and N) including
reachability, and (upon policy decision) summarized topology
information.
- Self-consistent information at the receiving level resulting from
any transformation (filter, summarize, etc.) and forwarding of
information from one Routing Controller (RC) to RC(s) at different
levels when multiple RCs are bound to a single RA.
- A mechanism to prevent re-introduction of information propagated
into the Level N RA's RC back to the adjacent level RA's RC from
which this information has been initially received.
Note: the number of hierarchical levels to be supported is routing
protocol specific and reflects a containment relationship.
Reachability information may be advertised either as a set of UNI
Transport Resource address prefixes, or a set of associated
Subnetwork Point Pool (SNPP) link IDs/SNPP link ID prefixes, assigned
and selected consistently in their applicability scope. The formats
of the control plane identifiers in a protocol realization are
implementation specific. Use of a routing protocol within a RA should
not restrict the choice of routing protocols for use in other RAs
(child or parent).
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As ASON does not restrict the control plane architecture choice,
either a co-located architecture or a physically separated
architecture may be used. A collection of links and nodes such as a
sub-network or RA must be able to represent itself to the wider
network as a single logical entity with only its external links
visible to the topology database.
5. Evaluation
This section evaluates support of existing IETF routing protocols
with respect to the requirements summarized from [RFC4258] in Section
4. Candidate routing protocols are IGP (OSPF and IS-IS) and BGP. The
latter is not addressed in the current version of this document. BGP
is not considered a candidate protocol mainly because of
- non-support of TE information exchange: each BGP router advertises
only its path to each destination in its vector for loop avoidance,
with no costs or hop counts; each BGP router knows little about
network topology
- BGP can only advertise routes that are eligible for use (local RIB)
or routing loops can occur; there is one best route per prefix, and
that is the route that is advertised.
- BGP is not widely deployed in optical equipment and networks
5.1 Terminology and Identification
- Pi is a physical (bearer/data/transport plane) node
- Li is a logical control plane entity that is associated to a
single data plane (abstract) node. The Li is identified by the
TE Router_ID. The latter is a control plane identifier defined as
follows:
. [RFC 3630]: Router_Address (top level) TLV of the Type 1 TE LSA
. [RFC 3784]: Traffic Engineering Router ID TLV (Type 134)
Note: this document does not define what the TE Router ID is. This
document simply states the use of the TE Router ID to
identify Li. [RFC 3630] and [RFC3784] provide the definitions.
- Ri is a logical control plane entity that is associated to a
control plane "router". The latter is the source for topology
information that it generates and shares with other control plane
"routers". The Ri is identified by the (advertising) Router_ID
. [RFC 2328]: Router ID (32-bit)
. [RFC 1195]: IS-IS System ID (48-bit)
The Router_ID, represented by Ri and that corresponds to the RC_ID
[RFC4258], does not enter into the identification of the logical
entities representing the data plane resources such as links. The
Routing DataBase (RDB) is associated to the Ri. Note that, in the
ASON context, an arrangement consisting of multiple Ri's
announcing routing information related to a single Li is under
evaluation.
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Aside from the Li/Pi mappings, these identifiers are not assumed to
be in a particular entity relationship except that the Ri may have
multiple Li in its scope. The relationship between Ri and Li is
simple at any moment in time: an Li may be advertised by only one Ri
at any time. However, an Ri may advertise a set of one or more Li's.
Thus, the routing protocol MUST be able to advertise multiple TE
Router IDs (see Section 5.7).
Note: Si is a control plane signaling function associated with one
or more Li. This document does not assume any specific constraint on
the relationship between Si and Li. This document does not discuss
issues of control plane accessibility for the signaling function,
and makes no assumptions about how control plane accessibility to
the Si is achieved.
5.2 RA Identification
G.7715.1 notes some necessary characteristics for RA identifiers,
e.g., that they may provide scope for the Ri, and that they must be
provisioned to be unique within an administrative domain. The RA ID
format itself is allowed to be derived from any global address space.
Provisioning of RA IDs for uniqueness is outside the scope of this
document.
Under these conditions, GMPLS link state routing protocols provide
the capability for RA Identification without further modification.
5.3 Routing Information Exchange
In this section, the focus is on routing information exchange Ri
entities (through routing adjacencies) within a single hierarchical
level. Routing information mapping between levels require specific
processing (see Section 5.5).
The control plane does not transport Pi identifiers as these are
data plane addresses for which the Li/Pi mapping is kept (link)
local - see for instance the transport LMP document [RFC4394] where
such an exchange is described. Example: the transport plane
identifier is the Pi (the identifier assigned to the physical
element) that could be for instance "666B.F999.AF10.222C", whereas
the control plane identifier is the Li (the identifier assigned by
the control plane), which could be for instance "192.0.2.1".
The control plane exchanges the control plane identifier information
but not the transport plane identifier information (i.e. not
"666B.F999.AF10.222C" but only "192.0.2.1"). The mapping Li/Pi is
kept local. So, when the Si receives a control plane message
requesting the use of "192.0.2.1", Si knows locally that this
information refers to the data plane entity identified by the
transport plane identifier "666B.F999.AF10.222C".
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Note also that the Li and Pi addressing spaces may be identical.
The control plane carries:
1) its view of the data plane link end-points and other link
connection end-points
2) the identifiers scoped by the Li's i.e. referred to as an
associated IPv4/IPv6 addressing space; note that these identifiers
may either be bundled TE link addresses or component link addresses
3) when using OSPF or ISIS as the IGP in support of traffic
engineering, [RFC 3477] RECOMMENDS that the Li value (referred to
the "LSR Router ID") to be set to the TE Router ID value.
Therefore, OSPF and IS-IS carry sufficient node identification
information without further modification.
5.3.1 Link Attributes
[RFC4258] provides a list of link attributes and characteristics
that need to be advertised by a routing protocol. All TE link
attributes and characteristics are currently handled by OSPF and IS-
IS (see Table 1) with the exception of Local Adaptation support.
Indeed, GMPLS routing does not currently consider the use of
dedicated TE link attribute(s) to describe the cross/inter-layer
relationships.
In addition, the representation of bandwidth requires further
consideration. GMPLS Routing defines an Interface Switching
Capability Descriptor (ISCD) that delivers information about the
(maximum/ minimum) bandwidth per priority of which an LSP can make
use. This information is usually used in combination with the
Unreserved Bandwidth sub-TLV that provides the amount of bandwidth
not yet reserved on a TE link.
In the ASON context, other bandwidth accounting representations are
possible, e.g., in terms of a set of tuples . The latter representation may also require
definition of additional signal types (from those defined in
[RFC3946]) to represent support of contiguously concatenated signals
i.e. STS-(3xN)c SPE / VC-4-Nc, N = 4, 16, 64, 256.
However, the method proposed in [RFC4202] is the most
straightforward without requiring any bandwidth accounting change
from an LSR perspective (in particular, when the ISCD sub-TLV
information is combined with the information provided by the
Unreserved Bandwidth sub-TLV).
Link Characteristics GMPLS OSPF
----------------------- ----------
Local SNPP link ID Link local part of the TE link identifier
sub-TLV [RFC4203]
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Remote SNPP link ID Link remote part of the TE link identifier
sub-TLV [RFC4203]
Signal Type Technology specific part of the Interface
Switching Capability Descriptor sub-TLV
[RFC4203]
Link Weight TE metric sub-TLV [RFC3630]
Resource Class Administrative Group sub-TLV [RFC3630]
Local Connection Types Switching Capability field part of the
Interface Switching Capability Descriptor
sub-TLV [RFC4203]
Link Capacity Unreserved bandwidth sub-TLV [RFC3630]
Max LSP Bandwidth part of the Interface
Switching Capability Descriptor sub-TLV
[RFC4203]
Link Availability Link Protection sub-TLV [RFC4203]
Diversity Support SRLG sub-TLV [RFC4203]
Local Adaptation support see above
Table 1. TE link Attributes in GMPLS OSPF-TE
Link Characteristics GMPLS IS-IS
----------------------- -----------
Local SNPP link ID Link local part of the TE link identifier
sub-TLV [RFC4205]
Remote SNPP link ID Link remote part of the TE link identifier
sub-TLV [RFC4205]
Signal Type Technology specific part of the Interface
Switching Capability Descriptor sub-TLV
[RFC4205]
Link Weight TE Default metric [RFC3784]
Resource Class Administrative Group sub-TLV [RFC3784]
Local Connection Types Switching Capability field part of the
Interface Switching Capability Descriptor
sub-TLV [RFC4205]
Link Capacity Unreserved bandwidth sub-TLV [RFC3784]
Max LSP Bandwidth part of the Interface
Switching Capability Descriptor sub-TLV
[GMPLS-ISIS]
Link Availability Link Protection sub-TLV [RFC4205]
Diversity Support SRLG sub-TLV [RFC4205]
Local Adaptation support see above
Table 2. TE link Attributes in GMPLS IS-IS-TE
Note: Link Attributes represent layer resource capabilities and
their utilization i.e. the IGP should be able to advertise these
attributes on a per-layer basis.
5.3.2 Node Attributes
Node attributes are the "Logical Node ID" (described in Section 5.1)
and the reachability information described in Section 5.3.3.
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5.3.3 Reachability Information
Advertisement of reachability can be achieved using the techniques
described in [OSPF-NODE] where the set of local addresses are
carried in an OSPF TE LSA node attribute TLV (a specific sub-TLV is
defined per address family, e.g., IPv4 and IPv6). However, [OSPF-
NODE] is restricted to advertisement of Host addresses and not
prefixes, and therefore requires enhancement (see below). Hence, in
order to advertise blocks of reachable address prefixes a
summarization mechanism is additionally required. This mechanism may
take the form of a prefix length (that indicates the number of
significant bits in the prefix) or a network mask.
A similar mechanism does not exist for IS-IS. Moreover, the Extended
IP Reachability TLV [RFC3784] focuses on IP reachable end-points
(terminating points), as its name indicates.
5.4 Routing Information Abstraction
G.7715.1 describes both static and dynamic methods for abstraction of
routing information for advertisement at a different level of the
routing hierarchy. However, the information that is advertised
continues to be in the form of link and node advertisements
consistent with the link state routing protocol used at that level.
Hence, no specific capabilities need to be added to the routing
protocol beyond the ability to locally identify when routing
information originates outside of a particular RA.
The methods used for abstraction of routing information are outside
the scope of GMPLS routing protocols.
5.5 Dissemination of routing information in support of multiple
hierarchical levels of RAs
G.7715.1 does not define specific mechanisms to support multiple
hierarchical levels of RAs, beyond the ability to support abstraction
as discussed above. However, if RCs bound to adjacent levels of the
RA hierarchy are allowed to redistribute routing information in both
directions between adjacent levels of the hierarchy without any
additional mechanisms, they would not be able to determine looping
of routing information.
To prevent this looping of routing information between levels, IS-IS
[RFC1195] allows only advertising routing information upward in the
level hierarchy, and disallows the advertising of routing
information downward in the hierarchy. [RFC2966] defines the up/down
bit to allow advertising downward in the hierarchy the "IP Internal
Reachability Information" TLV (Type 128) and "IP External
Reachability Information" TLV (Type 130). [RFC3784] extends its
applicability for the "Extended IP Reachability" TLV (Type 135).
Using this mechanism, the up/down bit is set to 0 when routing
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information is first injected into IS-IS. If routing information is
advertised from a higher level to a lower level, the up/down bit is
set to 1, indicating that it has traveled down the hierarchy.
Routing information that has the up/down bit set to 1 may only be
advertised down the hierarchy, i.e. to lower levels. This mechanism
applies independently of the number of levels. However, this
mechanism does not apply to the "Extended IS Reachability" TLV (Type
22) used to propagate the summarized topology (see Section 5.3),
traffic engineering information as listed in Table 1, as well as
reachability information (see Section 5.3.3).
OSPFv2 [RFC2328] prevents inter-area routes (which are learned from
area 0) from being passed back to area 0. However, GMPLS makes use of
Type 10 (area-local scope) LSAs to propagate TE information
[RFC3630], [RFC4202]. Type 10 Opaque LSAs are not flooded beyond the
borders of their associated area. It is therefore necessary to have
a means by which Type 10 Opaque LSA may carry the information that a
particular piece of routing information has been learned from a
higher level RC when propagated to a lower level RC. Any downward RC
from this level, which receives an LSA with this information would
omit the information in this LSA and thus not re-introduce this
information back into a higher level RC.
5.6 Routing Protocol Convergence
Link state protocols have been designed to propagate detected
topological changes (such as interface failures, link attributes
modification). The convergence period is short and involves a
minimum of routing information exchange.
Therefore, existing routing protocol convergence involves mechanisms
are sufficient for ASON applications.
5.7 Routing Information Scoping
The routing protocol MUST support a single Ri advertising on behalf
of more than one Li. Since each Li is identified by a unique
TE Router ID, the routing protocol MUST be able to advertise
multiple TE Router IDs. That is, for [RFC3630], multiple Router
Addresses and for [RFC3784] multiple Traffic Engineering Router Ids.
The Link sub-TLV currently part of the top level Link TLV associates
the link to the Router_ID. However, having the Ri advertising on
behalf of multiple Li's creates the following issue, as there is no
longer a 1:1 relationship between the Router_ID and the TE
Router_ID, but a 1:N relationship is possible (see Section 5.1). As
the link local and link remote (unnumbered) ID association may be
not unique per abstract node (per Li unicity), the advertisement
needs to indicate the remote Lj value and rely on the initial
discovery process to retrieve the {Li;Lj} relationship(s). In brief,
as unnumbered links have their ID defined on per Li bases, the
remote Lj needs to be identified to scope the link remote ID to the
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local Li. Therefore, the routing protocol MUST be able to
disambiguate the advertised TE links so that they can be associated
with the correct TE Router ID.
Moreover, when the Ri advertises on behalf multiple Li's, the
routing protocol MUST be able to disambiguate the advertised
reachability information (see Section 5.3.3) so that it can be
associated with the correct TE Router ID.
6. Evaluation Scenarios
The evaluation scenarios are the following; they are respectively
referred to as case 1, 2, 3, and 4.
In Figure 1 below:
- R3 represents an LSR with all components collocated.
- R2 shows how the "router" component may be disjoint from the node
- R1 shows how a single "router" may manage multiple nodes
------------------- -------
|R1 | |R2 |
| | | | ------
| L1 L2 L3 | | L4 | |R3 |
| : : : | | : | | |
| : : : | | : | | L5 |
Control ---+-----+-----+--- ---+--- | : |
Plane : : : : | : |
----------------+-----+-----+-----------+-------+---+--+-
Data : : : : | : |
Plane -- : -- -- | -- |
----|P1|--------|P3|--------|P4|------+-|P5|-+-
-- \ : / -- -- | -- |
\ -- / | |
|P2| ------
--
Figure 1. Evaluation Case 1, 2 and 3
Case 1 as represented refers either to direct links between edges or
"logical links" as shown in Figure 2 (or any combination of them)
------ ------
| | | |
| L1 | | L2 |
| : | | : |
| : R1| | : R2|
Control Plane --+--- --+---
Elements : :
------------------+-----------------------------+------------------
Data Plane : :
Elements : :
----+-----------------------------+-----
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| : : |
| --- --- --- |
| | |----------| P |----------| | |
---+--| | --- | |---+---
| | | | | |
| | P1|-------------------------| P2| |
| --- --- |
----------------------------------------
Figure 2. Case 1 with Logical Links
Another case (referred to as Case 4) is constituted by the Abstract
Node as represented in Figure 3. There is no internal structure
associated (externally) to the abstract node.
--------------
|R4 |
| |
| L6 |
| : |
| ...... |
---:------:---
Control Plane : :
+------+------+------+
Data Plane : :
---:------:---
|P8 : : |
| -- -- |
--+-|P |----|P |-+--
| -- -- |
--------------
Figure 3. Case 4: Abstract Node
Note: the "signaling function" i.e. the control plane entity that
processes the signaling messages (referred to as Si) is not
represented in these Figures.
7. Summary of Necessary Additions to OSPF and IS-IS
The following sections summarize the additions to be provided to
OSPF and IS-IS in support of ASON routing.
7.1 OSPFv2
Reachability Extend Node Attribute sub-TLVs to support
address prefixes (see Section 5.3.3)
Link Attributes Representation of cross/inter-layer
relationships in link top-level link TLV (see
Section 5.3.1)
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Optionally, provide for per signal-type
bandwidth accounting (see Section 5.3.1).
Scoping TE link advertisements to allow for retrieving
their respective local-remote TE Router_ID
relationship(s) (see Section 5.7)
Prefixes part of the reachability
advertisements (using Node Attribute top level
TLV) needs to be associated to their respective
local TE Router_ID (see Section 5.7)
Hierarchy Provide a mechanism by which Type 10 Opaque LSA
may carry the information that a particular
piece of routing information has been learned
from a higher level RC when propagated to a
lower level RC (such as to not re-introduce this
information back into a higher level RC)
7.2 IS-IS
Reachability Provide for reachability advertisement (in the
form of reachable TE prefixes)
Link Attributes Representation of cross/inter-layer
relationships in Extended IS Reachability TLV
(see Section 5.3.1)
Optionally, provide for per signal-type
bandwidth accounting (see Section 5.3.1).
Scoping Extended IS Reachability TLVs to allow for
retrieving their respective local-remote TE
Router_ID relationship(s) (see Section 5.7)
Prefixes part of the reachability advertisements
needs to be associated to their respective local
TE Router_ID (see Section 5.7)
Hierarchy Extend the up/down bit mechanisms to propagate
the summarized topology (see Section 5.3),
traffic engineering information as listed in
Table 1, as well as reachability information
(see Section 5.3.3).
8. Security Considerations
The introduction of a dynamic control plane to an ASON network
exposes it to additional security risks that may have been
controlled or limited by the use of management plane solutions. The
routing protocols play a part in the control plane and may be
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attacked so that they are unstable, or provide incorrect information
for use in path computation or by the signaling protocols.
Nevertheless, there is no reason why the control plane components
cannot be secured, and the security mechanisms developed for the
routing protocol and used within the Internet are equally applicable
within an ASON context.
[RFC4258] describes the requirements for security of routing
protocols for the Automatically Switched Optical Network. Reference
is made to [M.3016] that lays out the overall security objectives of
confidentiality, integrity, and accountability, and these are well
discussed for the Internet routing protocols in [THREATS].
A detailed discussion of routing threats and mechanisms, which are
currently deployed in operational networks to counter these
threats, is found in [OPSECPRACTICES]. A detailed listing of the
device capabilities that can be used to support these practices can
be found in [RFC3871].
9. IANA Considerations
This draft makes no requests for IANA action.
10. Acknowledgements
The authors would like to thank Adrian Farrel for having initiated
the proposal of an ASON Routing Solution Design Team and the ITU-T
SG15/Q14 for their careful review and input.
11. References
11.1 Normative References
[RFC1195] R.Callon, "Use of OSI IS-IS for Routing in TCP/IP and
Dual Environments", RFC 1195, December 1990.
[RFC2966] T.Li, T. Przygienda, and H. Smit et al. "Domain-wide
Prefix Distribution with Two-Level IS-IS", RFC 2966,
October 2000.
[RFC2328] J.Moy, "OSPF Version 2", RFC 2328, April 1998.
[RFC2119] S.Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3477] K.Kompella et al. "Signalling Unnumbered Links in
Resource ReSerVation Protocol - Traffic Engineering
(RSVP-TE)", RFC 3477, January 2003.
[RFC3630] D.Katz et al. "Traffic Engineering (TE) Extensions to
OSPF Version 2", RFC 3630, September 2003.
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[RFC3784] H.Smit and T.Li, "Intermediate System to Intermediate
System (IS-IS) Extensions for Traffic Engineering (TE),"
RFC 3784, June 2004.
[RFC3871] G.Jones, Ed., "Operational Security Requirements for
Large Internet Service Provider (ISP) IP Network
Infrastructure", RFC 3871, September 2004.
[RFC3946] E.Mannie, and D.Papadimitriou, (Editors) et al.,
"Generalized Multi-Protocol Label Switching Extensions
for SONET and SDH Control," RFC 3946, October 2004.
[RFC4202] K.Kompella (Editor) et al., "Routing Extensions in
Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4202, October 2005.
[RFC4203] K.Kompella, Y.Rekhter, et al, "OSPF Extensions in
Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4203, October 2005.
[RFC4205] K.Kompella, Y.Rekhter, et al, "Intermediate System
to Intermediate System (IS-IS) Extensions in Support
of Generalized Multi-Protocol Label Switching (GMPLS)",
RFC 4205, October 2005.
[RFC4258] D.Brungard et al. "Requirements for Generalized MPLS
(GMPLS) Routing for Automatically Switched Optical
Network (ASON)," RFC 4258, November 2005.
11.2 Informative References
[RFC4394] D.Fedyk et al., "A Transport Network View of the Link
Management Protocol (LMP)," RFC 4394, February 2006.
[OPSECPRACTICES] M.Kaeo, "Operational Security Current Practices",
Internet Draft (Work in progress), draft-ietf-opsec-
current-practices-02.txt, October 2005.
[OSPF-NODE] R.Aggarwal, and K.Kompella, "Advertising a Router's
Local Addresses in OSPF TE Extensions," Internet Draft,
(work in progress), draft-ietf-ospf-te-node-addr-
02.txt, March 2005.
[THREATS] A.Barbir et al., "Generic Threats to Routing
Protocols", Internet Draft (work in progress), draft-
ietf-rpsec-routing-threats-07.txt, October 2004.
For information on the availability of ITU Documents, please see
http://www.itu.int
[G.7715] ITU-T Rec. G.7715/Y.1306, "Architecture and
C.Hopps et al. - Expires January 2006 14
draft-ietf-ccamp-gmpls-ason-routing-eval-03.txt May 2006
Requirements for the Automatically Switched Optical
Network (ASON)," June 2002.
[G.7715.1] ITU-T Draft Rec. G.7715.1/Y.1706.1, "ASON Routing
Architecture and Requirements for Link State Protocols,"
November 2003.
[G.8080] ITU-T Rec. G.8080/Y.1304, "Architecture for the
Automatically Switched Optical Network (ASON),"
November 2001 (and Revision, January 2003).
11. Author's Addresses
Lyndon Ong (Ciena Corporation)
PO Box 308
Cupertino, CA 95015 , USA
Phone: +1 408 705 2978
EMail: lyong@ciena.com
Dimitri Papadimitriou (Alcatel)
Francis Wellensplein 1,
B-2018 Antwerpen, Belgium
Phone: +32 3 2408491
EMail: dimitri.papadimitriou@alcatel.be
Jonathan Sadler
1415 W. Diehl Rd
Naperville, IL 60563
EMail: jonathan.sadler@tellabs.com
Stephen Shew (Nortel Networks)
PO Box 3511 Station C
Ottawa, Ontario, CANADA K1Y 4H7
Phone: +1 613 7632462
EMail: sdshew@nortelnetworks.com
Dave Ward (Cisco Systems)
170 W. Tasman Dr.
San Jose, CA 95134 USA
Phone: +1-408-526-4000
EMail: dward@cisco.com
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Appendix 1: ASON Terminology
This document makes use of the following terms:
Administrative domain: (see Recommendation G.805) for the purposes of
[G7715.1] an administrative domain represents the extent of resources
which belong to a single player such as a network operator, a service
provider, or an end-user. Administrative domains of different players
do not overlap amongst themselves.
Control plane: performs the call control and connection control
functions. Through signaling, the control plane sets up and releases
connections, and may restore a connection in case of a failure.
(Control) Domain: represents a collection of (control) entities that
are grouped for a particular purpose. The control plane is subdivided
into domains matching administrative domains. Within an
administrative domain, further subdivisions of the control plane are
recursively applied. A routing control domain is an abstract entity
that hides the details of the RC distribution.
External NNI (E-NNI): interfaces are located between protocol
controllers between control domains.
Internal NNI (I-NNI): interfaces are located between protocol
controllers within control domains.
Link: (see Recommendation G.805) a "topological component" which
describes a fixed relationship between a "subnetwork" or "access
group" and another "subnetwork" or "access group". Links are not
limited to being provided by a single server trail.
Management plane: performs management functions for the Transport
Plane, the control plane and the system as a whole. It also provides
coordination between all the planes. The following management
functional areas are performed in the management plane: performance,
fault, configuration, accounting and security management
Management domain: (see Recommendation G.805) a management domain
defines a collection of managed objects which are grouped to meet
organizational requirements according to geography, technology,
policy or other structure, and for a number of functional areas such
as configuration, security, (FCAPS), for the purpose of providing
control in a consistent manner. Management domains can be disjoint,
contained or overlapping. As such the resources within an
administrative domain can be distributed into several possible
overlapping management domains. The same resource can therefore
belong to several management domains simultaneously, but a management
domain shall not cross the border of an administrative domain.
Subnetwork Point (SNP): The SNP is a control plane abstraction that
represents an actual or potential transport plane resource. SNPs (in
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different subnetwork partitions) may represent the same transport
resource. A one-to-one correspondence should not be assumed.
Subnetwork Point Pool (SNPP): A set of SNPs that are grouped together
for the purposes of routing.
Termination Connection Point (TCP): A TCP represents the output of a
Trail Termination function or the input to a Trail Termination Sink
function.
Transport plane: provides bi-directional or unidirectional transfer
of user information, from one location to another. It can also
provide transfer of some control and network management information.
The Transport Plane is layered; it is equivalent to the Transport
Network defined in G.805 Recommendation.
User Network Interface (UNI): interfaces are located between protocol
controllers between a user and a control domain. Note: there is no
routing function associated with a UNI reference point.
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Appendix 2: ASON Routing Terminology
This document makes use of the following terms:
Routing Area (RA): a RA represents a partition of the data plane and
its identifier is used within the control plane as the representation
of this partition. Per [G.8080] a RA is defined by a set of sub-
networks, the links that interconnect them, and the interfaces
representing the ends of the links exiting that RA. A RA may contain
smaller RAs inter-connected by links. The limit of subdivision
results in a RA that contains two sub-networks interconnected by a
single link.
Routing Database (RDB): repository for the local topology, network
topology, reachability, and other routing information that is updated
as part of the routing information exchange and may additionally
contain information that is configured. The RDB may contain routing
information for more than one Routing Area (RA).
Routing Components: ASON routing architecture functions. These
functions can be classified as protocol independent (Link Resource
Manager or LRM, Routing Controller or RC) and protocol specific
(Protocol Controller or PC).
Routing Controller (RC): handles (abstract) information needed for
routing and the routing information exchange with peering RCs by
operating on the RDB. The RC has access to a view of the RDB. The RC
is protocol independent.
Note: Since the RDB may contain routing information pertaining to
multiple RAs (and possibly to multiple layer networks), the RCs
accessing the RDB may share the routing information.
Link Resource Manager (LRM): supplies all the relevant component and
TE link information to the RC. It informs the RC about any state
changes of the link resources it controls.
Protocol Controller (PC): handles protocol specific message exchanges
according to the reference point over which the information is
exchanged (e.g. E-NNI, I-NNI), and internal exchanges with the RC.
The PC function is protocol dependent.
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